Gyroscopes



Oct. 6, 1959 GARNER 2,907,212

GYROSCOPES Filed April 2, 1958 United States Patent 6 GYROSCOPES Georges Garnier, Asnieres, France, assignor to Air- Eqnipement, Asnieres, France, a French company Application April 2, 1958, Serial No. 725,930 Claims priority, application France April 3, 1957 7 Claims. (Cl. 745.1)

The present invention relates to gyroscopes having two degrees of freedom and more particularly concerns means for caging the gyroscope, that is, for ensuring that its axis of rotation is oriented in -a direction parallel with a reference direction.

At the present time, electromagnetic devices are used for this purpose which act through the medium of cams on each of the two pivot axes of the gyroscope so as to bring the latter into a well-determined position (caging) relative to the support of the apparatus. A part of the caging devices is therefore supported by the outer movable frame of the gyroscope which complicates problems of balancing, size and electrical feed.

The object of the invention is tosimplify the caging means of a gyroscope and the invention is characterized by the fact that the caging of a pivotable support means of the gyroscope, preferably the inner ring, is obtained by utilization of the precession movements of the gyroscope, which movements are produced by the application of a correcting torque exerted (without producing movement) on another pivotable support means of the gyroscope, for example the outer ring, whose pivot axis is at 90 to the pivot axis of the first-mentioned sup port means. I

In a preferred embodiment of this caging system, the latter is also characterized by the following features and combinations thereof:

The correcting or compensating torque is exerted by electromagnetic means;

The electromagnetic means producing the correcting torque comprise two electromagnets which are fixed and are disposed on either side of the pivot axis of the outer ring and two studs of magnetic material without remanence fixed to the outer ring in such manner as to be offset relative to the electromagnets and to be capable of co-operating with the latter so as to produce a torque on either side of the pivot axis of the outer ring;

The electromagnetic means producing the correcting torque are advantageously automatically controlled by a potentiometer whose resistance is unitary with the outer ring of the gyroscope andwhose slider is actuated by the inner ring of the gyroscope;

The potentiometer controlling the electromagnetic means producing the correcting torque is advantageously the potentiometer which already exists and is used in the transmission of the normal utilization signals of the gyroscope, and switching means are provided for connecting said potentiometer to the control circuits of said electromagnetic means during the caging period and to the circuit of utilization after the caging period;

The switching means of the potentiometer are controlled automatically preferably by means of a time-delay relay;

The caging of the outer ring relative to the fixed stand of the gyroscope is obtained, in the known manner, by means of a cam fixed to said ring and with which cooperates the armature of an electromagnet fixed to the stand, this electromagnet being controlled automatically 2,907,2l2 Patented Oct. 6, 1959 preferably through the medium of the time-delay relay system controlling the switching means;

The time-delay relay system comprises two time-delay relays of which one, having a short time delay, controls the electromagnet obtaining the caging by means of a cam and a relay controlling the circuit of the electromagnets producing the correcting torque, whereas the second time-delay relay, having a long time delay,- controls the first relay as well as a switching relay arranged to connect the potentiometer of the gyroscope firstly to a differential relay controlling selectively the current supply to one or the other of the correcting electromagnets during the caging period by precession, and then to the normal utilization circuit of this potentiometer at the end of the caging period;

The time-delay relays are of the double blade type controlling the opening of a switch which is ordinarily closed when the relay is not excited.

Further features and advantages of the invention will be apparent from the ensuing description of one embodiment of a gyroscope improved in accordance with the invention, with reference to the accompanying drawing, to which the invention is in no way restricted.

In the drawing:

Fig. 1 is an elevational view of the gyroscope one of the support sides of the stand having been removed for the sake of clarity;

Fig. 2 is avieW at to Fig. 1, and

Fig. 3 is a diagram of the control circuits of the caging system of the gyroscope.

In the embodiment shown in the drawing, the reference character 1 designates the fixed stand of the gyroscope, 2 the outer frame or ring of non-magnetic material, and 3 the inner frame or ring in which is mounted the rotor driven by a three-phase electric motor 4 (Fig. 3).

The caging of the outer ring 2 is obtained by means of a cam 5 of suitable profile fixed to this ring and with which co-operates a roller 6 carried by the plunger 7 of an electromagnet 8 fixed to the stand 1.

The caging of the inner ring 3 is obtained by utilization of the precessional movements of the gyroscope, in the manner indicated hereinafter, by means of two electromagnets 10a and 10b fixed to the stand 1 and capable of co-operating respectively with studs 9a and 9b of magnetic metal having no remanence fixed to the outer ring 2, which studs are slightly eccentric relative to their respective electromagnets so that when the caging has been obtained relative to the axis X-X and the plunger 7 has been returned to its normal position by its return spring (the electromagnet being no longer excited), each of the electromagnets 10a and 10b is capable of exerting a torque on the outer ring 2.

When, after having started up the motor 4, the outer ring 2 is caged by means of the electromagnet 8 which urges the roller 6 against the periphery of the cam so as to cause the latter to pivot (with the ring 2) until the roller enters the recess 5a and blocks the ring in the caged position about or relative to the pivot axis X-X, the reaction of the rotor of the gyroscope is manigestesdK by a pivoting of the inner ring about the axis To produce thereafter the caging of the inner ring 3 by a pivotal movement about the axis YY, it is sumcient after having ceased to excite the electromagnet 8, to excite either of the electromagnets 10a and 10b. This electromagnet then exerts a torque on the stud associated therewith and it is this torque which, owing to the phenomenon of precession, causes the inner ring 3 to pivot. That one of the electromagnets 10a and 10b which had been, excited is ceased to be excited as soon as the inner ring 3 reaches its caged'position.

In this way the mounting of a cam on the inner ring and an electromagnet (similar to the electromagnet 8) on the outer ring is dispensed with which facilitates solution of balancing problems;

Power supplied to the electromagnets 10a and 10b is advantageously controlled by the existing signalization potentiometer 11 whose resistance 11a is unitary with the outer ring 2 and Whose slider 11b is unitary with the pivot axis or spindle of the inner ring 3, the output circuit of the potentiometer being advantageously automatically switched by a control system having timc-- delay relays of the type shown in Fig. 3.

In this diagram, 12 designates the general double switch which simultaneously controls the supply of current to the motor 4 by connection to a three-phase supply A, for example at 400 c.p.s., and the supply of Current, by con nection to a direct current supply B for example at 27 volts, to the assembly of the relay control system, the relay 8 and the electromagnets 10a and 1012 producing the correcting torque.

This control system comprises a relay 13 having a long time delay controlled by a bimetallicstrip arrangement and so arranged that its operative contact is ordinarily closed, this contact only opening at the end of 30 seconds, the excitation winding of this relay being directly connected to the direct current terminals of the control system. The contact of this relay controls:

(a) The circuit of the caging electromagnet 8.

(b) The excitation circuit of a relay 14 whose ordinarily closed contact only opens when the winding of said relay is excited.

(c) The excitation circuit of a time-delay relay 15 having a short time delay controlled by a bimetallic strip and so arranged that its operative contact is ordinarily closed and opens at the end of five seconds this contact also controlling the circuit of the cagiug electromagnet 8 and the excitation circuit of the relay 14.

(d) The excitation circuit of a relay 16 arranged to switch the three terminals of the potentiometer 11 of the normal utilization circuit U of this potentiometer to the terminals of a difierential relay 1'7 and vice-versa, the arrangement of the relay 16 being such that the" potentiometer 11 is only connected to the relay 17 when the relay 16 is inoperative, that is, during the time delay period of the relay 13, and that the potentiometer is connected to the circuit U as soon as the relay 16 is excited, that is, as soon as the relay 13 reaches the end of its time delay.

The differential relay 17 comprises two opposed windings controlling a single armature connected to one of the direct current terminals and capable of coming into contact with either one of two working studs respectively connected to the windings of the torque'producing electromagnets 1 3a and 1012 which are, furthermore, connected to the other direct current terminal (through the closed contact of the non-excited relay 14), the arrangement of: this relay 17 being such that its armature is under the control of that one of the windings whose action is preponderant due to the position of the slider of the potentiometer 11.

The control system just described operates in the following manner:

When unexcited, the potentiometer 11 is connected to the difiercntial relay 17 and the contacts of the relays 13, 14 and 15 are closed.

When the general switch 12 is closed, the motor 4 is supplied with current (the rotor of the gyroscope starts to rotate) and the relays 13, 14 and 15 and the electromagnet 8 are supplied with current. The contacts of the relays 13 and 15 still remain closed, but the contact of tl e relay 14 opens, so that the electromagnets 10a and 19b still receive no current. The relay 16 is unexcited the two terminals of its windings having the same polarity. On the other hand, the electromagnet 8 ensures the caging of the gyroscope about the pivot axis XX.

At the end of fivc seconds (time delay of the relay 15, which corresponds to that necessary for the caging about the axis XX) the contact of the bimetallic strip relay 15 opens; the electromagnet 8 and the relay 14 cease to receive current and the contact of the relay 14 closes so that the two windings 10a and 1% are now connected to one of the terminals C; The winding of the relay 16 is still unexcited and the potentiometer 11 remains connected to the differential relay 17 which can thus supply current to either one of the electromagnets 10a and 1%, which ensures the caging of the gyroscope about the axis YY by production of a torque about the axis XX and utilization of the phenomenon of precession (as mentioned hereinbefore).

At the end of 30 seconds (at the end of which period caging is terminated) the contact of the bimetallic strip relay 13 (whose winding continues to receive current so long as the general switch 12 remains closed) opens, which finally interrupts excitation of the relays 14 and 15 and excitation of the electromagnet 8. Simultaneously, the winding of the relay 16 is now receiving current so that this relay interrupts the feed to the differential relay 17 (which in turn cuts oil the feed to the torque-producing electromagnets 1th: and 10b) and connects the potentiometer 11 to the utilization circuit U of the gyroscope.

It will be understood that as soon as the main switch 12 is closed, at the same time as the motor is started up, the gyroscope is first positively caged in the course of a first period of 5 seconds relative to the axis X--X and then caged, by utilization of the phenomenon of precession, during a second period of 25 seconds relative to the axis YY.

Although a specific embodiment of the invention has been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

What I claim is:

1. In a device for caging a gyroscope having a rotative body, an inner pivotable support means for supporting the rotative body and permitting the latter to turn about its axis of rotation, an outer pivotable support means for supporting the inner support means and permitting the latter to pivot about an axis perpendicular to the axis of rotation of the rotative body, a fixed support means for supporting the outer support means and permitting the latter to pivot about an axis perpendicular to the aforementioned axis, electromagnetic caging means mounted on the fixed support means and arranged to exert electromagnetically a torque on the outer support means, about the axis of the latter, and thus cause the inner support means to pivot, by precession, under the effect of said torque, the provision of electromechanical caging means for holding, when starting, the outer support means in a given position relative to the fixed sup port means.

2. Device as claimed in claim 1, wherein the electromechanical caging means comprise an elcctromagnet fixed to the fixed support means, a movable armature controlled by said electromagnet, and a cam unitary with the outer support means and with which cam said armature is cooperable for holding said cam in a given position.

3. Device as claimed in claim 1, wherein the electromagnetic caging means comprise two electromagnets fixed to the fixed support means on each side of the pivot axis E the outer support means and two armatures cooperable with said electromagnets and fixed to the outer support means on either side of the pivot axis of the latter.

4. Device as claimed in claim 1, further comprising a potentiometer having a resistance unitary with the outer support means and a slider unitary with the inner support means, said potentiometer being connected to the electromagnetic caging means for controlling the latter as a function of the angular position of the inner sup port means relative to the outer support means.

5. Device as claimed in claim 2, further comprising con 5 6 tact means for automatically controlling in succession the ing of a contact ordinarily closed when the relay is unelectromechanical caging means and then the electromagexcited. netic caging means.

6. Device as claimed in claim 5, wherein the contact References Cited in h l Of this Patent means comprises time-delay relays controlling the coming 5 UNITED STATES PATENTS into action of the electromechanical and electromagnetic caging means. 1,390,471 Sundhaussen Sept. 13, 1921 7. Device as claimed in claim 6, wherein the time-de- 2,297,265 Von Manteufiel Sept. 29, 1942 lay relays are of the thermal type controlling the open- 

